This task takes all @reset() or @reset(selector) properties and goes off to find any matches, copying those properties as if they were selector includes. However, @reset() will *only* copy those properties defined on classes that are in @reset{} blocks, copy on the sub-block level, and don't override *any* rules of the same name. Copying on the sub-block level means that given: @reset{ div { a:b; } } that .class { c:d; div { @reset(); e:f; } } evaluates to .class { c:d; } .class div { a:b; e:f;} Naturally, @reset(selector) will match on the actual select passed.